Hello all,My company is using an older version of ME, but it works fine for our purposes.For our domains, we use ProofPoint Mail Filtering So incoming email goes to Proof Point -> Our MailEnable Servers -> Our Exchange serverNow some emails coming from Proof Point to ME arrive fine, no issue. And then get sent on to our Exchange server.

Other emails however are stuck on Proof Point servers.The servers connect to our ME servers, go through the initial handshake, and then get to DATA in the log file and then that is it.All in the same second.SMTP Activity log looks like this:

Wondering if anyone has any ideas?I have white listed the Proof Point servers.The error they see/report is:

Status: Deferred Summary: This message could not be delivered yet, but will be retried periodically until either success or expiry Timestamp: 22:23:19 EST, Thursday 08 February 2018 Last delivery response: delivery temporarily suspended: conversation with [216.54.104.221] timed out while sending message body